Known in the art, there is the U.S. Pat. No. 5,399,897 of B. T. Cunningham and P. V. Richard, describing a microstructure comprising a surface member and at least one leg, a proximate end of the leg being connected to a substrate and the distant end thereof being connected to the surface member. The leg is a multi layer leg comprising at least one dielectric layer and one electrically conductive layer.
Also known in the art, there are the U.S. Pat. No. 5,021,663 of L. J. Hornbeck and the U.S. Pat. No. 5,288,649 of W. F. Keenan. The supports described in these two patents are made entirely of metal or metal alloy films.
The following US patents also describe microstructures:
U.S. Pat. No. Issue Date Inventor (s) 5,010,251 Apr. 23, 1991 Grinberg et al 5,286,976 Feb. 15, 1994 Cole 5,300,915 Apr. 5, 1994 Higashi et al 5,602,393 Feb. 11, 1997 Gerard 5,672,903 Sept. 30, 1997 Butler et al 5,688,699 Nov. 18, 1997 Cunningham et al
Referring now to FIG. 1, there is shown a perspective schematic view of a typical microbridge structure of the prior art. The microbridge structure shown in FIG. 1 consists of a microstructure 40 suspended over a substrate layer 41, and two inclined legs 42. The microstructure 40 provides a support for a sensing layer 43. The microstructure 40 is equipped with slots 44 cut through its entire thickness in order to elongate the path of heat conduction from the microstructure 40 to the substrate layer 41, and thus improving thermal isolation of this microstructure. The microstructure 40 is also equipped with a reticulated metal layer 45. The metal layer 45 partially overlapping the sensing layer 43 provides an electrically conductive path between the sensing layer 43 and the legs 42.
The legs 42 provide a support for the microstructure 40. The proximate ends of each leg are connected to the substrate layer 41 via electrical contact pads 46. The distant ends of the legs are connected to the microstructure 40. Each leg 42 is a multi layer leg consisting of a reticulated dielectric layer 47 and a reticulated electrically conductive layer 48 providing an electrically conductive path between the substrate layer 41 via contact pads 46 and the electrically conductive layer 45 of the microstructure 40 via contacts 49.
A drawback with the microbridge structures of the prior art is that when several microbridge structures are mounted side by side over a given area of the substrate layer 41 to form the sensitive surface, a portion of the area is needed to accommodate the legs of the microbridge structures. Such portion of the area that is needed to accommodate the legs is useless for sensing purposes and therefor limit the detecting capabilities of the microbridge structures.
An object of the present invention is to provide a microstructure bridge that can be used in a detector array made of several microstructure bridges mounted side by side within a given area to obtain a detector array with improved detecting capability.
Another object of the present invention is also to provided a method for making a microstructure bridge that can be used in a detector array made of several microstructure bridges mounted side by side within a given area to obtain a detector array with improved detecting capability.